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At least 1,333 records · Page 74Linked to original sources
PubMed1989

Radiation effects in Caenorhabditis elegans, mutagenesis by high and low LET ionizing radiation.

The nematode C. elegans was used to measure the effectiveness of high-energy ionized particles in the induction of 3 types of genetic lesions. Recessive lethal mutations in a 40-map unit autosomal region, sterility, and X-chromosome nondisjunction or damage were investigated. Induction rates were measured as a function of linear energy transfer, LET infinity, for 9 ions of atomic number 1-57 accelerated at the BEVALAC accelerator. Linear kinetics were observed for all 3 types of lesions within the dose/fluence ranges tested and varied strongly as a function of particle LET infinity. Relative Biological Effectiveness (RBE) values of up to 4.2 were measured and action cross sections were calculated and compared to mutagenic responses in other systems.

Animals↗
PubMed1989

Combined radiation-protective and radiation-sensitizing agents. IV: Measurement of intracellular protector concentrations.

Radiosensitization of hypoxic V79 Chinese hamster cells by 0.5 mM misonidazole at approximately 0-4 degrees C is substantially enhanced by pretreating the cells overnight with 0.1 mM buthionine sulfoximine, which lowers the cellular glutathione content to 5% of control values (from 4 mM to approximately 0.2 mM). The enhanced sensitization is reversed by concentrations of exogenous cysteine that are much lower (0.02 mM) than the original glutathione content. Reduced Co-enzyme A affords reversal of the enhancing effect at concentrations of about 1 mM. Sodium ascorbate gives no protection at all even at concentrations of 2 mM. The intracellular concentration of the reducing agents was measured using a spin-through oil technique. There was no diffusion of Co-A (MW greater than 750) or ascorbate (excluded by charge) into the cells. In contrast, cysteine was rapidly concentrated by factors of 4-10, even at the low temperatures used. Extracellular ascorbate's inability to radioprotect argues against electron transfer across the cell membrane as a mechanism for radioprotection. This mechanism could have explained the ability of exogenous thiols to radioprotect in former studies using glutathione, and in the present studies using Co-A. The potential of cysteine to be concentrated by cells poses a problem in the interpretation of "exogenous protection" by non-diffusing thiols, since trace contamination by cysteine could lead to the actual protection observed. Cysteine could also be formed by exchange reactions of exogenous thiols with the disulfide of cysteine, present in all media formulations.

Animals↗
PubMed2002

The United Kingdom Childhood Cancer Study of exposure to domestic sources of ionising radiation: 2: gamma radiation.

This article reports measurements of household levels of gamma and cosmic rays at the addresses of children with cancer at the time of diagnosis and six months before, and of similar data at the addresses of control children. There is no indication of increased risk with increasing dose rates either in matched or unmatched analyses, with or without adjustment for deprivation. Sub-division by diagnostic group did not reveal any association with any specific types of malignancy. Studies of the relationship between household gamma rays and radon concentration show no evidence of any interactions.

Air Pollution, Indoor↗